1. Field of the Invention
The present invention relates to a friction stirring and joining apparatus that performs friction stirring and joining on a workpiece.
2. Description of Related Art
Friction stirring and joining is known as one of the methods of joining a workpiece including two members. The friction stirring and joining makes a tool rotated in a state where a junction of the workpiece is pressurized by a predetermined pressurization force in a surface called a shoulder surface of the tool, thereby making frictional heat generated on a workpiece surface to soften the workpiece with this frictional heat to join the workpiece.
In such friction stirring and joining, a level difference, that is, unevenness may occur on the upper surfaces of abutted portions between joined members as the workpiece due to deformation of the workpiece when being formed, the heat deformation during the friction stirring and joining, or the like. When the friction stirring and joining is performed in a state where this unevenness has occurred, there is a possibility that poor joining, such as a tunnel-like cavity or a groove, may occur in a joining portion, thereby joining strength may deteriorate. For example, a technique of preventing occurrence of such poor joining is disclosed in Japanese Unexamined Patent Application, First Publication No. 2000-202645.
In the friction stirring and joining apparatus disclosed in JP-A-2000-202645, the friction stirring and joining is performed in a state where the unevenness that is a level difference between two joined members is made to fall within a predetermined range, while the end portion upper surfaces of the joined members are pressurized by a pressure roller on an extension in the advancing direction of a rotary tool. This pressure roller is formed such that a pressing shaft that supports the pressure roller is bent from a halfway position in the vertical direction so that a pressurizing portion is brought as close to the rotary tool as possible.
However, in the technique disclosed in Japanese Unexamined Patent Application, First Publication No. 2000-202645, if a strong joining pressure is made to act as the pressing shaft of the pressure roller is bent, a large moment is generated in this load imparting section, which may be damaged. Additionally, in a case where a high-rigidity material is used for the pressing shaft in order to prevent damage, a large rise in cost will be incurred.
The invention has been made in consideration of such circumstances, and an object thereof is to provide a friction stirring and joining apparatus that can suppress unevenness while controlling costs and preventing damage.